[time-nuts] WWVB teensy BPSK early experiments

Wed Nov 4 09:44:15 UTC 2020

Paul,

Thanks for the info.  I took some good measurements on the signal coming in
on one of the small ferrite antennas when the signal was fairly OK - I
measured
4-9 uV.  I haven't done this same measurement yet on the antenna I'm
testing on - I didn't think I could be over driving the mic input but
that's a possibility.  Also, I haven't done a great job in assembling this
project - I need to neaten things up and maybe encase in a housing
that will reject RFI, etc.

Thanks for mentioning this.  I have ordered one of those nice antennas from
Stormwise but I'm still waiting to receive it.

73's,
John
AJ6BC

On Tue, Nov 3, 2020 at 12:13 PM paul swed <paulswedb at gmail.com> wrote:

> By the way thats leads. A typo.
> It just hit me I had to cut the signal down so that the signal graph was in
> the middle.
> On the large antenna thats a 330K resistor to a 100K pot.
> For the wwvb simulator its simply the 100K pot turned up about 2/3rds of
> the way. The simulator is something like 60 uv out.
> Maybe you have a overdrive issue.
> Regards
> Paul.
>
> On Tue, Nov 3, 2020 at 9:49 AM paul swed <paulswedb at gmail.com> wrote:
>
> > John
> > Yes I have used Chris's code to decode the wwvb AM timecode. I am in
> > Boston so just about as far away as you can get. Though maybe Florida is
> > further. But Boston is in more of a null from wwvb.
> > Granted the antenna is a tuned 10' X 10' 800 ft of wire loop and preamp
> > mentioned numerous times on time-nuts. It reliably during the day
> delivers
> > 100 uv at the end of the coax.
> > I found the teensy wwvb sdr really worked best during the day. With
> > respect to power for the antenna its just a power inserter I built, 8 Mh
> > choke, 100 ohm resistor, .47 uf coupling cap to the teensy. No magic at
> all.
> > One very serious issue with the teensy is that the audio module must be
> > directly stacked on to the cpu. I originally used 3" leeds those little
> > jumpers. It makes a mess of the clock signals.
> > Regards
> > Paul.
> >
> > On Mon, Nov 2, 2020 at 10:55 PM John C. Westmoreland, P.E. <
> > john at westmorelandengineering.com> wrote:
> >
> >> Paul,
> >>
> >> Have you successfully decoded WWVB with Chris's code?
> >>
> >> I haven't gotten that to work.
> >>
> >> I'm using the same antenna set up I've used that works with the multipsk
> >> Clock program to decode WWVB that will decode fairly reliably as long as
> >> atmospheric conditions are favorable.
> >>
> >> Note, if using the Arduino IDE and you're connected to a PC; it will
> >> sometimes set the clock on the TFT to the PC's clock; I'm mentioning
> that
> >> since some that try this could think their set up is synced to WWVB when
> >> it
> >> actually grabbed time from the PC.  Maybe the loader from Teensy does
> >> that;
> >> I haven't looked close enough yet to know for sure what's setting that.
> >>
> >> Glad you're making progress with your approach.
> >>
> >> 73's,
> >> John
> >> AJ6BC
> >>
> >>
> >> On Mon, Nov 2, 2020, 18:20 paul swed <paulswedb at gmail.com> wrote:
> >>
> >> > John thats exactly what Chris did. Its the teensywwvb.ino. It decodes
> >> the
> >> > AM timecode just as the DCF code does. In fact Chris's code is derived
> >> from
> >> > the DCF code with the changes you are asking about and it works.
> >> Download
> >> > his solution and read the comments throughout. The original DCF
> comments
> >> > are in it also.
> >> >
> >> > Its the starting point for the tinkering I am doing towards a BPSK
> SDR.
> >> > Thats a big leap for me.
> >> > What the code gives you is the frontend gain, followed by a bandpass
> >> > filter. Multiplier that mixes the LO and incoming signal to a lowpass
> >> > filter. Then on to AM detection and AGC.
> >> >
> >> > If you don't care to install the arduino IDE with teensy extension
> just
> >> use
> >> > notepad ++ to look at the code. Pretty exciting.
> >> >
> >> > Regards
> >> > Paul
> >> > WB8TSL
> >> >
> >> > On Mon, Nov 2, 2020 at 8:24 PM John C. Westmoreland, P.E. <
> >> > john at westmorelandengineering.com> wrote:
> >> >
> >> > > Hello Time Nuts,
> >> > >
> >> > > I have a question -
> >> > >
> >> > > Has anyone been successful getting WWVB to decode using the example
> >> for
> >> > > DCF77 and making the changes for WWVB?
> >> > >
> >> > > Chris has his own approach - it's interesting - but on my setup at
> >> least
> >> > I
> >> > > haven't been successful with it - maybe it's my antenna - not sure
> >> just
> >> > > yet.
> >> > > Also - my screen eventually 'whites-out' after running that for a
> >> while -
> >> > > meaning - the screen goes completely white and I don't know what's
> >> doing
> >> > > that yet - I suppose it's a bug of some sort.
> >> > >
> >> > > But, with the DCF77 approach - it appears to identify bits OK - with
> >> the
> >> > > code having only minimal changes - so I'd like to go down that path.
> >> > >
> >> > > Note - I have a fork here - but it's debug - and not sure it's worth
> >> > > anything other than looking at some of the data that's being dumped.
> >> > > https://github.com/jwestmoreland/Teensy-DCF77
> >> > >
> >> > > For DC7FF - the AM is just 0.2ms (1) and 0.1ms (0) with no AM at the
> >> > minute
> >> > > marker, but WWVB is a little more complicated -
> >> > > 0.2ms (0), 0.5ms (1), and 0.8 ms (Marker) - 2 consecutive markers
> mark
> >> > the
> >> > > end of current minute/beginning of next minute.
> >> > >
> >> > > The DCF77 code seems to take some advantage of the signal
> level/timing
> >> > and
> >> > > the dimensions of the TFT display for
> >> > > displaying the signaling - at least that's what it appears to me
> right
> >> > now
> >> > > unless I'm looking at this wrong - I guess that isn't
> >> > > a big deal until you try to deal with the marker timing for WWVB -
> of
> >> > > course I could be looking at this wrong right now too.
> >> > >
> >> > > Maybe trying something like the Goertzel algorithm like KE9NS has
> >> done in
> >> > > his work with WWV is worth taking a look at too with
> >> > > this setup.
> >> > >
> >> > > 73's,
> >> > > John
> >> > > AJ6BC
> >> > >
> >> > >
> >> > >
> >> > >
> >> > >
> >> > > On Sun, Nov 1, 2020 at 10:50 AM Mike Feher <mfeher at eozinc.com>
> wrote:
> >> > >
> >> > > > Too bad I am an old retired hardware engineer and know nothing
> about
> >> > > these
> >> > > > new SW controlled devices. Have Fun - Regards - Mike
> >> > > >
> >> > > > Mike B. Feher, N4FS
> >> > > > 89 Arnold Blvd.
> >> > > > Howell NJ 07731
> >> > > > 848-245-9115
> >> > > >
> >> > > > -----Original Message-----
> >> > > > From: time-nuts <time-nuts-bounces at lists.febo.com> On Behalf Of
> >> paul
> >> > > swed
> >> > > > Sent: Sunday, November 1, 2020 12:48 PM
> >> > > > To: Discussion of precise time and frequency measurement <
> >> > > > time-nuts at lists.febo.com>
> >> > > > Subject: Re: [time-nuts] WWVB teensy BPSK early experiments
> >> > > >
> >> > > > John sent the link on the teensy wwvb AM receiver. It can easily
> be
> >> > > > shifted to other frequencies. Using the work Frank dcf77 and then
> >> Chris
> >> > > > wwvb did with the PJRC audio design tool gives quite a bit of
> >> insight
> >> > to
> >> > > > the work that was done.
> >> > > > The system assumes a sample rate of 192Khz. That limits the
> receive
> >> > range
> >> > > > to about 98KHz.
> >> > > > I have not been able to confirm the rate I am using is 192Khz and
> >> when
> >> > > the
> >> > > > set command is used its not recognized. So somethings up.
> >> > > > The design Chris has essentially is a microphone input with some
> 38
> >> db
> >> > of
> >> > > > gain feeding a bandpass filter around 60 KHz to a multiplier (RF
> >> mixer)
> >> > > > then a low pass filter. Chris and Franks design is much more than
> >> these
> >> > > few
> >> > > > words with spectrum display, signal level, and AGC.
> >> > > > So without any effort the frontend solution is sitting in the
> teensy
> >> > that
> >> > > > cuts out a bunch of typical wiring. Granted its not as tight as
> >> > discrete
> >> > > > components can be. But its a chunk of software code. No digi key
> >> orders
> >> > > for
> >> > > > L & Cs... :-) The output of the chain is 600 Hz audio that does
> >> contain
> >> > > the
> >> > > > phase changes.
> >> > > >
> >> > > > But the trick is creating the true I & Q channels. Not an issue to
> >> add
> >> > a
> >> > > > second multiplier and chain did that last night. But at someplace
> a
> >> 90
> >> > > > degree phase change or delay needs to occur.
> >> > > > Or as suggested a hilbert transform.
> >> > > > Regards
> >> > > > Paul
> >> > > > WB8TSL
> >> > > >
> >> > > >
> >> > > >
> >> > > >
> >> > > > _______________________________________________
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> >> > > >
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